The proposed research will be divided into the following categories: 1) Further improvements of the artificial heart designed and tested in animal experments in the last grant year. Main improvements will be focused on the following points: a. The diaphragm and the housing will be made in one piece by one process which can be achieved by a more advanced design and fabrication technique than the present one piece construction. b. Development of built-in valves, which has not been accomplished during the last grant year, will be continued. 2) Testing of the blood pump in the mock loop using echographic techniques will be continued to determine optimal system designs and improve control-driving modes of operation. Application of this technique in experimental animals with the artificial heart implanted will be studied. 3) In addition to various pathophysiological, hematologic and blood gas studies in chronic animals, cardiovascular drug tests will be continued. BIBLIOGRAPHIC REFERENCES: Kito, Y., Honda, T., Gibson, W.H., and Akutsu, T: Long-term hemodynamic effects of the total artificial heart. Bull. Texas Heart Inst. 3:85, 1976. Akutsu, T: Artificial organs, cardiac surgery and artificial heart. Modern Medical Treatment 3:80, 1976 (Japan).